1. Field of the Invention
The present invention is a device for providing deployable, adjustable, controlled flex and lateral suspension movement to a motorcycle chassis.
2. Background Information
This invention is a device for providing deployable, adjustable, controlled flex and lateral suspension movement to a motorcycle chassis for the purpose of enhancing handling characteristics when leaned-over, and at slower speeds, but without compromising stability when the motorcycle is upright, and at high speeds.
Over the last twenty years or so, advances in motorcycle chassis and tire design have delivered great improvements in handling characteristics, especially with respect to high-speed stability. Unlike earlier chassis designs, which were often flexible to the point that dangerous instability would surface at any elevated speed, modern performance oriented motorcycles remain generally stable in most situations. While motorcycling has clearly benefitted from these advancements in frame, suspension, and tire technology, one area that arguably needs more attention is that of leaned-over traction and rider “feel.” Many earlier flex-prone designs, while often frightening at elevated speeds and when mostly upright, generally remained more-or-less stable and offered good “feel” and compliance to surface irregularities when leaned-over, as when cornering. While the older “flexible” chassis absorbed some of the energy of a bump, the newer “rigid” chassis cannot. The modern chassis are rigid to the point that when leaned-over, irregularities in the road surface sometimes deflect the tires in an arc about the center of mass of the machine, resulting in a loss of traction. One might expect the suspension to absorb this bump energy, but this is not always possible. Looking at the forces acting on the motorcycle offers insight as to why very rigid chassis don't always perform as well as they might. As illustrated in drawing FIGS. 1 and 2, the bump force which acts on the suspension when leaned-over, as when cornering, is a portion of that which acts on the suspension when the motorcycle is upright. Additionally, centrifugal force tends to pre-load the suspension when cornering, making the suspension effectively stiffer. Some increase in friction in the telescopic front fork may also be present when cornering, as it is loaded at an angle to its normal plane of operation. In essence, when cornering, a lesser force is available to act on suspension that is less likely to be moved by that force. Because of this, in some cases, when an irregularity in the road surface is encountered, the tires may leave the road surface or be unloaded to the point that they lose traction. This can result in chatter, instability, or even momentary “high-side” crash inducing losses of traction. Since the suspension must accommodate braking dive forces, stability, comfort, and cornering clearance constraints, softer springs and modified damping are not a viable option to deal with this lessened force. A fully active suspension system may be an answer to this problem, but complexity and power requirements make it impractical at present. It is apparent that some chassis flex or lateral suspension movement can be beneficial to handling in some situations, and detrimental in others.
Applicant has invented a lateral suspension device, which provides deployable, adjustable, controlled flex and lateral suspension movement to a motorcycle chassis. The amount of deflection and the force required to initiate the deflection is adjustable. The device may be deployed as desired per rider preference and conditions. In two embodiments, the device is actuated automatically per inputs to a programmable logic unit. A third embodiment is manually adjusted.